LAS VEGAS—Ken Norton never fell down in 39 rounds of professional boxing with Muhammad Ali. But Ken Norton did fall down on Jan. 23, 2012, while posing for a picture after a press conference at the Lou Ruvo Center for Brain Health in Las Vegas. I saw it happen. Ken Norton, the esteemed special guest at the press luncheon, shuffled to the front of the room amid the Cleveland Clinic doctors and public relations representatives, let go of his walker, and slowly, oh so slowly, tilted backward and fell through the step-and-repeat backdrop. The doctors helped him up. There's not much else they can do for him.

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"Brain damage is beautiful," my boxing coach told me. "You don't have those ... interregnums between your thoughts. They just come. It's great if you're a poet." He is also a poet. His brain damage is of the (relatively) genial sort, affecting mostly his memory rather than his motor skills, rendering him a kind of absent-minded professor who can still spar.

His opinion is in the minority, though. Most people who box for any length of time, whether recreationally or competitively, have a certain amount of dread concerning what might be happening to their precious brains. "Yes, I worry about it," one young woman at Gleason's Gym told me in between rounds. She works in education. She cast her eyes about the building. "Most of these girls fighting here are like, dog walkers ..." she trailed off. Left unstated: The more you want to fight, the less you had better want to use your brain outside of a ring-based environment.

Blood is not the scary part of boxing. Blood is an annoyance, a split lip, a split eyebrow, lending a vivid bit of color to a fight, but taking little physical toll. Far more scary is the thought of the unseen damage being inflicted inside one's skull. Blood is cleaned up with a rag and some Vaseline and adrenaline and stitches and a scar. Brain damage is not cleaned up, ever.

For pro fighters, it doesn't pay to voice any concern about this. Once you've made the choice to fight for a living, worrying will only slow you down. For some fighters this manifests as a proud, ignorant bravado; for others, as grim acceptance, another cost of doing business. The Lou Ruvo Brain Center in Vegas is in the midst of multiyear study of pro fighters and their brains, to try to determine just what happens to them, and when, and why, and how and if it can be prevented. Last week they had a press conference to inform sportswriters of their progress.

One finds that this is a topic that offers no comfort as you learn more about it. Dr. Charles Bernick, who's leading the study, briefly ran down a list of the things we don't know about brain injuries: what dose of trauma is needed to inflict them; whether damage is a function of the number of impacts, the duration of impacts, the frequency, the intensity, or something else; what genetic risk factors may be involved; why some people are more susceptible to injury than others; how to detect brain damage early; how it progresses; or, of course, how to fix it.

Supremely uncomforting. According to Bernick, none of the speculation—over whether boxing is safer than MMA or football, or whether hits in practice are the real culprit, or whether lots of small shots are worse than a few big concussions—is based on real scientific knowledge. We just don't know. After all this had been duly explained, I asked him if he had any safety tips I could pass on to those already involved in these sports, who don't have five or 10 or 20 years to wait for results to come in. He paused. "No," he answered. "I don't have any tips."

All we really know about brain damage in boxing is that it happens, and that it will fuck you up. This fact was demonstrated by the presence at lunch of Leon Spinks and Ken Norton, two great heavyweights turned shells. They may well have a lot going on their minds, but outwardly, both give the appearance of vacancy. Norton now shuffles forward on his walker and speaks in a low growl that bears little resemblance to language. Spinks seem permanently slack-jawed, uncomprehending, not all there. Halfway through lunch he fell asleep at the table, and was gently roused by his minder.

Top Rank promoter Bob Arum, the most powerful man in boxing, was also at the lunch. He said all the right things about the need for a long-term health-care plan for boxers. I would think that if anyone in the world could make that happen, it would be Bob Arum. But in Bob Arum's view, that responsibility lies with the state of Nevada. The state of Nevada's athletic commission does not see eye to eye with him on this issue. Diego Magdalena, an active fighter in attendance, said that he would know when to stop boxing by monitoring his own health. "You can't rely on the athlete to diagnose himself," objected Arum.

Meanwhile, fighters still have no long term health plan.

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A.J. Liebling, the greatest of all boxing writers, once made the following plea for boxing's redeeming qualities: "If a novelist who lived exclusively on applecores won the Nobel Prize, vegetarians would chorus that the repulsive nutriment had invigorated his brain. But when the prize goes to Ernest Hemingway, who has been a not particularly evasive boxer for years, no one rises to point out that the percussion has apparently stimulated his intellection."